Bifuel system for gas engines



1 July 927 c. CORNWELL BIFUEL SYSTEM FOR GAS ENGINES Filed May 13, 1925 INVENTOR. UM M M Y I ATTOR EYS.

. Patented July 12, 1927;

UNITED STATE-S om GORNWELL, on OAKLAND, GALIQFOBNIA.

I IBIFUEL SYSTEM FOR GAS ENGINES.

Application and ma 13, 1925. Serial 110.2%),909.

This invention relates to a bi-fuel system for gas engines, particularly for the utilization of the heavy fuel oils, I am aware that engines for using a light volatile fuel oil as gasolene for starting and a heavier running fuel oil, such as kerosene, after the engine a has become warmed up, are not new but have "been in use for a considerable period of time. My invention does not, therefore, relate to this idea broadly but to certain improvement therein. It is the general object of my invention to provide an improved bifuel system for gasengines of this type.

In this description the term gas engine is to be taken in its common meaning as describing an internal combustion engine -designed for the use of volatile fuels. The difference in theheat of vaporization of different weight fuel oils requires apparatus for handling and vaporizing these oils independently and delivering the oil vapors independently to the gas intake port of the engine. Gasolene, being more volatile than heavier fuel oil, vaporizes at a much lower temperature, gasolene ordinarily vaporizing at atmospheric temperature whereas heavier fuel oil requires a heating thereof to a higher temperature. My invention, therefore, contemplates two independent carburetdrs for vaporizing two difierent-weight fuel oils, means for providing heated air of the-proper vaporizing temperature to the carburetor using the heavier oil and independeht-manifolds for independently conducting these different temperatured oil vapors to the gas intake port of the engine. It A is an object of my invention to provide an improved bi-fuel system for gas engines embodying these features.

It is a further object of my invention to r6vide in combination with the apparatus Just defined a thermostatically controlled valve by which heated air of the proper -temerature is automatically supplied to the eavier oil carburetor which valve control is simpler, and more accurate and eflicient than such controlling devices heretofore known. In the accompanying drawing I have shown certain specific embodiments of my invention, but it will be understood that the invention can be otherwise embodied and that the drawing is not to be construed as defining orlimiting the scope of the invenvaporized valve or gate 19 ti on, the claim appended to this specificat1on being relied upon for that purpose.

Referring to the figures of the drawing.

Flg. 1 is an elevation partially in section of a gas engine embodying the improved features of my invention;

Fig. 2 is an enlarged longitudinal sectional view of the thermostatic air controlling mechanism shown in Fig. 1.

In the drawing, 1 indicates an internal combustion engine havinga crank shaft 2, a piston 3, a gas intake port 4, and an exhaust port 5 leading outwardly through an exhaust pipe 6. Two carburetors 7 and 8 are mounted adacent to the engine and connect to the intake port 4 by independent manifolds 9 and 10. As the operating temperature of light and heavy oils vary greatly it has been found necessary to provide two separate manifolds msulated from each other by an air space or other insulating material.

I'have illustrated the carburetor 7 and its manifold'9 as smaller than the carburetor 8 and its manifold 10 since ordinarily the carburetor 7 uses a light fuel as gasolene only for starting and warming up the enginer Fuel is supplied to the carburetors 7 and 8 from pipes 11 and 12 and the flow of fuel therefrom is controlled by throttle valves 13 and 14. The carburetor 7 is also provided with an auxiliary valve 15 for admitting air thereto in the manner hereinafter described.

Heated air is supplied to the heavier oil carburetor 8 from a heater 16 surrounding exhaust pipe 6. A tube 17 connects this heater with the carburetor. A portion 18 of this tube as seen 1n detail in Fig. 2 is provided with a thermostatically controlled for automatically admittiiig cool air thereinto when excessive heat ,therein requires. As illustrated, this valve 19 is pivoted to the tube at 20 and normally closes the opening 21 into the tube; The valve controlling element comprises two bars of metal 22 and 23, having different coeflicients of expansion, riveted together and rigidly mounted on studs 24 centrally within the tube. The free to the Valve by a pivoted ing nuts 26.

In Figure 2 the end of the bars is connected bolt 25 and adjustbar and valve are shown in full lines in the normal position; that is, when. the air in the Difl'erent grades of fuel require the vaporizing air to be heated to different temperatures and the adjusting nuts 26 provide means for adjusting the mechanism toopen the valve the proper amount and permit cool air to enter when the air within the pipe reaches an excessive temperature. The bar 22, which may be of an aluminum or copper alloy, has a greater coefiicient of expansion than the bar 23, which may be of iron, and therefore upon excessive heating the double bar will pipe 18 is unheated.

15 is partially closed in a manner to give an over-rich mixture of gasolene'vapor. The valve 14 of the carburetor 8 is then slightly opened, thus permitting a flow of air to be drawn from the heater 16 through the carburetor, tube, and manifold. In this manner the engine exhaust operates to qulckly heat the carburetor 8 and itsparts to the vaporizing temperature. ,No fuel is admitted to the carburetor 8 until the heated air passing therethrough has warmed the carburetor and its parts suflicientl toinsure the vaporization of the hea el.

When the car uretor 8 and its parts become sufliciently heated, fuel oil is admitted to the carburetor from the pipe 12 and the engine is permitted to operate fora short time on both gasolene and, oil. When load is applied to the engine, the exhaust heat increases the, temperature of the air in the pipe 17 and the gasolene is then entirely out o permitting the engine to run on oil alone. When the gasolene supply to the carburetor 7 is shut off the valve 15 thereof can be opened if desired'to supply additional air to the oil va or through the manifold 9.

The use 0 the independent manifolds and the cooperating mechanism as illustrated r and described provides for fully warming u the oil carburetor and its manifold to the 0H vaporizing temperature while starting the engine on gasolene. It will be understood that the gasolene vapor, bein of a lower temperature, would considera ly interfere with this warming-up operation were such gasolene vapor to pass through the oil maniold 10. When the engine is full operating on oil the thermostatic valve will automatically control the temperature of the air supplied to the oil carburetor as will be underwith This follows It 'is desirable in practice that the engine be able to operate at part load, this necessitating low compression in the cylinders. If the thermostat is set so as to provide the necessary heat to give a clean burning gas at low compression, the gas vapor is liable to pre-ignite when the throttle is opened Wide and the engine is operated on full compression. By using the auxiliary air, valve 15 a supply of cold air can be admitted to the heated vapor coming from-the carburetor 8 thereby cooling the same below the point of ignition and supplying additional oxygen for the complete combustion of the vapor. the well known principle'that an engine at fullcompression will burn a leaner mixture than at low compression.

This arrangement also provides a means of operating continuously at variable loads entailing less than full compression.

The apparatus when constructed in accordance with operate to start the engine on gasolene in a minimum of time and with a minimum consumption of fuel. During this time the oil carburetor and its associated pa ts are heated to the proper temperature in a manner permitting the exclusive use of the cheaper oil fuel within the period of a very few minutes necessary to heat up the engine. Thereafter.

the thermostatically controlled valve operates to automatically supply the carburetor 8 heated air of the proper vaporizing temperature whereby the the heavier fuel without further attention or consideration. .If it is desiredto use the engine on load instantly or before the carburetor 8 has become heated, a larger gaso- H provided, the operation lene carburetor is thereof beingthe same but with a larger expenditure of gasolene.

' No special carburetor is specified, as sev-- eral standard makes of carburetor have been found suitable for both oil and gasolene as used in this apparatus. Nor is any special type of retort for heating the intake air necessary, as such retorts or stoves may be varied greatlyto suit the needs of different installations. I have found by actual use that with this apparatus it is possible to operate a gas or gasolene engine oncheap and-heavy oils with little. or no carbon deposit and almost perfect combustion of the heavy oil. I

.Having thus described my I claim and desire to secure ent is:

invention, what by Letters Pat- An internal combustion engine having'an intake port and an engine operates onv e port, means providing a conduit formy improved system will conductingair heated from the exhaust gases mospheric air thereinto, thie air con- L into the second carburetor, thermostatic-com ducted throu h the first manifold into the trolled means for adinitting cool air to the intake port w erein it mixes with the heavy conduit to maintain a constant temperature fuel vapor from the second carburetor to 5 and a relatively large manually-controlled form an explosive mixture of the proper air valve cooperating with t the first carproportionsa p buretor and adapted to admit outside at- CARL CORNWELL. 

